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From: Oliver Fromme <olli@lurza.secnetix.de>
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To: avg@freebsd.org (Andriy Gapon)
Date: Tue, 21 Dec 2010 11:59:10 +0100 (CET)
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Cc: lev@serebryakov.spb.ru, freebsd-geom@freebsd.org
Subject: Re: FreeBSD 8.2-PRERELASE doesn't see slice on SDHC card in
	cardreader
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Andriy Gapon wrote:
 > on 21/12/2010 10:11 Oliver Fromme said the following:
 > > Lev Serebryakov <lev@serebryakov.spb.ru> wrote:
 > > >   I  inserted 16Gb SDHC card, with one FAT32 slice (it is card from my
 > > >  PDA). After that I've tried:
 > > > [...]
 > > > blob# ls /dev/da0*
 > > > /dev/da0
 > > 
 > > # /bin/dd if=/dev/null of=/dev/da0 count=0
 > > 
 > > Then try again.
 > 
 > $ true > /dev/da0
 > 
 > is shorter and less prone to typos.

It's shorter, but not less prone to typos, I think.

If you misspell the command, or your shell's completion
happens to have a bad day, the '>' output redirection will
destroy whatever is on the device.  On the other hand,
dd's "of=..." syntax is not understood by other commands,
so it is safe even if you misstype the command.  And even
if you accidentally write /dev/zero instead of /dev/null,
the count=0 will save you (and vice versa).

Of course it's probably a good idea to wrap the command
in a shell alias or function (I would call it "probe-sd"
or similar), so neither the length of the command nor the
possibility of typos plays a role ...

Best regards
   Oliver

-- 
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
Handelsregister: Registergericht Muenchen, HRA 74606,  Geschäftsfuehrung:
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chen, HRB 125758,  Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart

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